Method of preparing nonturbid homogeneous solutions and dispersions of colloids and products so prepared



Patented July 3,1345 v A UNITEDQSTATE'S PATENT OFFICE Fritz w; n. Muellen Binghamton, N. Y., assignor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application September20, 1940, e I SeriaiyNo. 357,608 l 15 Claims. (Cl. lot-L205) The present invention relates to a method of, drate character possessbuilding units chieilyconpreparing non-turbid solutions or dispersions sisting of hexuronic acids. These hexuronicacids from carbohydrate-containing gums which upon areusually aggregated either in chainor ring casting may be convertedinto a, non-turbid tllm structure (see; Hinton, Fruit Pectins, 1940), or layer suitable for use particularly in photogwhich form completely insoluble salts such'as calraphy. The inventionalso embraces the noncium pectate' or calcium alginate. turbid solutions and dispersions and the layers Such natural colloids as pectin may possess prepared therefrom.- varying calcium content depending onthe han- The carbohydrate-containing gums (pages 490 dling of the extracts. The calciumsalts present" et seq., vol. III and pages 112 et seq., vol. I of in fruit juicesand'extracts provide the source of Dictionary of Applied Chemistry/{by Thorpe) the calcium which at least partially neutralizes which are colloidal in character haveinherent carboxylic groups of pectin becoming exposed by film-forming possibilities. Among such gums may unavoidable partial deesterification owing to pecbe mentioned the alginates, pectin, agar-agar, tase action. If thedeesterification proceeds too Carageen (Chondrus mispus), extracts of lichen farrthe character of the calcium salts formed be- (Cetraria. islandica) and the like. For instance, sins t appr a h that f th mpl t ly .d they have potential possibilities in the photomethylated pectic acid and the tendency of pecgraphic field in the formationof adhesive layers tin to become insoluble increases. for strip film, soluble surface and back coating In other extracts of carbohydrate-containing layers and the like. The potentialities oi. these-.20 gums, as Carageen, Laminaria. digitata, and the materials, however, have never been realized, due like, the action of enzymes easily sets free carto the fact that it was heretofore impossible to boxylic groups, whichmay then form insoluble prepare absolutely non-turbid, clear solutions or calcium salts, thus binding in anon-ionizable dispersions capable ofdrying with asmoothsurform the calcium. or alkaline earth metals, usu-' face and without showing inhomogeneities in ally abundantly present in such extracts.

structure. It is believed to be-manifest that in It is obvious.that the dialysismethod is incaphotography the layers of film must be clear, pable of effecting removal of the organically transparent, free from; haze and capable of i'ormbound calcium in these cases. It 'has been stated ing entirely smooth surfaces, in order for the fllm that the chemical precipitation method was unto be adequate for the purposes intended. Besuccessful. When resorting to this method. it cause of the tendency of thegums in question to wasiound that calcium precipitating acids eflect produce. turbid solutions, the solutions thereof a degradation of the colloids which resulted in a when cast lead to layers. incapable of giving the' great reduction in the viscosity thereof or in the desired smoothness of surface and transparency. gelling power. The viscosity and the gel strength It is known that .the turbidity of the aqueous isa very-desirable feature in thepractical appli solutions or dispersions of animal colloids like 7 cation of the colloidal solutions and therefore the gelatine is caused by insoluble inorganic salts i great reduction thereof by the precipitatlonmethusually formed by the alkaline earth metals, cal-. dmakes this method unsatisfactory. In addicium in particular. These inorganic salts, such tion this method often leads to the inclusion in as calcium phosphate, are capable of ionization 40 the solutions of other undesirable anions. at a certain pH and, as a consequence, may be en.- In the case of pectin the acid treatment would .tirely removed fromthe colloids by dialysis orv primarily cause de-esteriflcation and partially electro-dialysis or chemically by precipitation convert the pectin to pectic acid, the'acid groups with suitable acids, the. anions of which will preof which bind calcium, even taking it from tap cipitate calcium ions, as for instance oxalic acid 46 water, thereby making the application of this and the like. Neither. of these two methods, 'oolloid more "unsuitable for photogr ph 'p rhoweven-is satisfactory for removing the turbidity poses. Itis therefore the organically bound calfrom the carbohydrate-containing colloids such cium occurring in carbohydrate-containing gums as those mentioned above. Investigations have, which hasprevented the application of these colshown that unlike animal colloids, the carbohy- 50 loids for photographic purposes. crate-containing gums contain alkaline; earth I have now discovered that the chemical agents metals in an organically bound, non ionized known to the art as water-softening agents, which rather thanin an inorganically bound condition. remove the hardness from water by a conversion 7 It isknown that in contrast to such colloids as of the salts causing the hardness to water solugelatine, a protein, the building units (amino- 5s ble salts, can dissolve these insoluble organic'calacids) of which do not form insoluble alkaline cium compounds and thus counteract, even withearth metal salts, certain colloids of carbohys out their removal, their-deleterious eflects on the 2 i s wsw homogeneity or the solution so vitally necessary the alginate into complete solution. The solu-v ior photographic purposes. r l *tion may then serve as a surface coating or as an Suitable softenin agents which remove the anti-halation coating.

.hardness from water by conversion of the salts, Y E l 2 causing the hardness, to water soluble salts are 5 camp 8 the alkali metal hexametaphosphates, partic- Ah ad e e is. prep r from the compilation ularly the sodium salt, the alkali metal salts of a p e n to expedite the spreadi i rer polyaminmpolycarboxylic acids s, or, there is .added a small amount or an amide 2,130,505), the alkali metal salts of trirnethyl- Such as is described 1 P- 1, 2, 7 The aminotricarboxylic acids (U. s. P. 2,168,181), and 0 hexametanhosphate p a es to preve t a y for the like. The chemical mechanism by which the motion of an insoluble calcium salt of these we conversion is efl'ected, is not definitely known. 8 8 when the film r 'l the l hfl v It is possible that the water-softening agents contacts water containing calcium ions.

operate in the aqueous solutions and dispersions Example 3 of the colloids in the same manner asthey do in 15 i A solution is prepared as described in Example removing. the hardness of water. 7 At any rate, 7 despite the insolubility oi the organic calcium salts but there is used in lieu of sodium haematoand the complexity .of the composition or the col-' Phwhhate, the salt 01 the m-9 lolds. the water-softening agents convert these cairboxync acid of Elflmple'l 01 P- 2. .5 calcium salts to the soluble-state without any 20 n Example 4 detrimental eflect upon the colloid itself. The utilization of such water-softening agents to pro- A solution is Prepared as descnbed in Example duce non-turbid solutions and dispersions capable exceipt for the tact theme-Memes or being cast to form non-turbid layers oi carbos: m t of tmnethylmuno'm hydrate-containing gums,layers or this character XY 0 M of S. P. 2,168,181.

and compositionls1 for producing the same comprise Example 5 the objects of t is invention.

The my be in my cherishes testis For instance in co -pending application Serial No. at room mm emture The 80mm is mm 285,498,fl1ed July 20, 1939, now U. s. P. 2,275,617, so then heated 2 w flea 2181 h it has been proposed to form adhesive layersior and thereafter quick-1' c5018 d P 3 in stripillmtrom vegetable mucllages. In such cases arm f this d i t 1 1th b a smooth and even surface oi the adhesive layer 5 m s er e g: t y is of greatest interest to insure the production of z: g y e a 2 3 a smooth permanent support. The addition to gfl g fl the vegetable Images f watermmnmegifembel gig filflo ei atled s oiuble photoagents, such as those previous y mentioned, results in a decided improvement in the adhesive graphic layers of colilomal gums anapmcess conditioning such gums for such use, which has it is often desirable to completely dissolve surm !ace-, anti-ahrasion-, anti-halation coatings and gga gg gg a is 3:3; 33%;? 8 the like consisting of vegetable mucilages alter th t bid 81 p t c n these layers have served their purpose. By inu y a g corporation of the water-softening agents such h on may a; complete solution is facilitated by reason of the eswe ayer Sm an a com fact that the. agents prevent the formation. of in- Example 8 soluble calcium s'alts in'processing solutions made 0.1 to 4% of pectin is dissolved ill-0.2 to 0.6%

up with ordinary tap water or during the washing of the film. In addition there are instances in Solution of so iu a t phosphate. 'Illil which it is desirable to produce photographic layamount is usually sufficient t clear p and? tilters containing carbonates, sulfates, oxalates, olel 0f Pectin Selutiohs from V r u cri'lin ate or other fatty acid radicals. pinicultiesdde (apples. citrus fruits. ch solution may to turbidity often result when the layers are comthen Serve a Surface coating or as an antis d of th carbohydrate-containing gumsv t, halation coating or as an adhesive layer. has been found that nov precipitation leading to NOW therefore I -1 1 1 ss for conditioning carbohydrateturbidity ensues upon the addition of such saltsii a water-softening agent-is included in the layer. mhtammg gums e in forming hon-turbid The amount of the water-softening agent whic photosmphielayers which comprises addins to should be employed varies depending upon the an aqueous solution or dispersion 0! such gums content of alkaline earth metal present in the an ammmt a water-soluble gum or'colloid. It is, however, a simple expedient 888m; .sllmcieht effectively v r he amto ascertain the amount of the water-soitening line earth metal Salt thereof mm wateirflhluhle at which should be em 10 ed b addin the salts I age p y y g fined in claim Lwherein ater-soi'tenin a cut to the solution or dis r- 'n e a e w 8 g s no ign w gi 05 the water-softening agent is an alkali metal salt n untila test sam le show 5w p or hexametaphospha after being; cast and dried. y

The following examples serve to illustrate the The PTOCBSS as defined 1n 81 wherein invention, although it is to be understoodthat the ricted e of a polyamino-polycarboxylic acid. H

' the water-soiteningagent is an alkalimetal salt 0.1 to'3% or sodium or 'ammoniurnalginate is of trimethylamino-tricarbokylic acid. dissolved in 0.2 to 0.5% solution-oi sodium hexa 5. a com osition capable of rorming'non-turbid metaphosphate (Calgon) This amountis usually photographic layers-onzcasting thereof, comprisrequired to bring the insoluble salts contained in 16 in: an aqueous solution or dispersion of a carbolayers contemplated by said application Again matured into Patent No. 2,330,905, dated October the water-softening agent is an alkali metal salt invention is notrest 7o 4. The process as defined in claim 1, wherein hydrate-containing gum and a small amount of a water-soluble water-softening agent capable of eflectlvely converting the water-insoluble alkaline earth ,metal salts of the gum into watersoluble salts.

6. A composition capable of forming nonturbid photographic layers on casting thereof,

9. Non-turbid photographic adhesive layers of the composition of c1aim'5.

comprising an aqueous solution or dispersion of a vegetable gum and a small amount of sodium hexametaphosph-ate.

'I. A composition capable of forming nonturbid photographic layers on casting thereof,

comprising an aqueous solution or dispersion of a vegetable gum and .a small amount of a water soluble salt of a polyamino-polycarboxylic acid.

8. A composition capable of forming nonturbid photographic layers on castingv thereof, comprising an aqueous solution or dispersion of a vegetable gum and a small amount of a water soluble salt of a trimethylaminotricarboxylic id e v 10. Non-turbid photographic adhesive layers of the composition of claim 6.

11. Non-turbid photographic adhesive layers of the composition of claim 'l.

12. Non-turbid photographic adhesive layers of the composition of claim8.

'15. The process as defined in claim 1 wherein the carbohydrate-containing gum is ammonium alginate and the water-softening agent is a poly- 20 amino-polycarboxylic,acid.

FRITZ W. H. MUELLER. 

